This invention is related to a method for decreasing the foaming tendency of hydrocarbons. More specifically, the present invention is directed at a method for reducing the tendency for lube basestocks to foam.
Foaming has been a major problem in the manufacture of hydrocarbon products, such as lubricating oils. If the lubricating oils demonstrate excessive foaming with agitation or turbulent flow during use, the lubricant no longer may be delivered effectively to the moving parts as a continuous liquid stream. In addition, foaming may result in overflow losses of the lubricant. Therefore, foaming ultimately may result in inadequate lubrication and mechanical failure.
Efforts to reduce the foaming tendency of lubricating oils have not been entirely satisfactory. When a lubricating oil exhibits an undesirable foaming tendency, conventional treatment generally has comprised the addition of foam suppressors, such as polyalkylsiloxanes and heavy polyesters. However, use of foam suppressors is not always effective, and represents an additional manufacturing expense. Moreover, addition of a foam suppressor to the lubricating oil may lead to blending difficulties because the limited solubility of foam suppressors may make optimal dispersion difficult to achieve. In addition, there are limits to the amount of foam suppressor which can be added without increasing the tendency of the oil to entrain air, which decreases the ability of the oil to lubricate. Thus, some lubricating base oils produced cannot be utilized for their most desirable end uses.
U.S. Pat. No. 4,152,249 discloses that a hydrocarbon, such as a motor oil, can be purified by passing the hydrocarbon through an adsorption resin, such as polycondensates of phenol and/or resorcinol, with formaldehyde and/or 2-formaldehyde, and the porous polycondensates of aliphatic ketones with bis-arylaldehydic compounds optionally comprising one or more phenol and/or pyridyl groups between the two terminal aromatic aldehyde groups.
U.S. Pat. No. 3,830,730 discloses a method of improving the Viscosity Index (VI) of hydrocarbon lubricating charge oils, which comprises substantially completely absorbing the hydrocarbon charge oil on a solid absorbent and then diluting the absorbent with a liquid selective for the higher VI components in the absorbed oil. Among the preferred solid absorbents disclosed are bauxite, calcined bauxite, alumina oxide, silicon oxide, clay, bentonite, diatomaceous earth, Fuller's earth, bone char, charcoal, magnesium silicate, activated kaolin, silica-alumina and zeolites.
U.S. Pat. No. 3,620,969 discloses the use of crystalline zeolitic alumino-silicates for the removal of sulfur compounds from a petroleum feedstock.
U.S. Pat. No. 3,542,669 is directed at the removal of arsenic and arsenic derivatives from petroleum feedstreams by adsorption on activated carbon which preferably had been acid-impregnated.
While all of these patents disclose passing a hydrocarbon feedstock through an adsorption or absorption zone, none of these patents recognizes that the foaming tendency of hydrocarbon feedstocks can be reduced by passing the hydrocarbon feedstock through an adsorption zone.
Accordingly, it would be desirable to provide a process which reduces the foaming tendency of hydrocarbon feedstocks while minimizing or reducing the necessity for the addition of foam suppressors.
It also would be desirable to provide a regenerable process for reducing the foaming tendency of hydrocarbon feedstocks.
It also would be advantageous to provide a process which could be retrofitted onto existing hydrocarbon processing facilities without lengthy shutdown or extensive modifications.
It also would be desirable to provide a process which requires relatively low utility consumption, relatively little maintenance and relatively little operator attention.
The present invention is directed at a method for reducing hydrocarbon foaming by passing the hydrocarbon through an adsorption zone which remove trace components in the hydrocarbon that promote foaming. The adsorption zone preferably is regenerable and preferably comprises a solid exhibiting basic properties, i.e., the solid can be titrated with an acid to measure its basicity.